An in-depth report on how people with diabetes can eat healthy diets and manage their blood glucose.
According to the ADA, the most important component of a weight loss plan is not its dietary composition, but whether or not a person can stick with it. The ADA has found that both low-carb and low-fat diets work equally well, and patients may have a personal preference for one plan or the other.
Patients with kidney problems need to limit their protein intake and should not replace carbohydrates with large amounts of protein foods. (However, patients who are on dialysis require more protein.)
The two major forms of diabetes are type 1. previously called insulin-dependent diabetes mellitus (IDDM) or juvenile-onset diabetes, and type 2. previously called non-insulin-dependent diabetes mellitus (NIDDM) or maturity-onset diabetes.
Both type 1 and type 2 diabetes share one central feature: elevated blood sugar (glucose ) levels due to absolute or relative insufficiencies of insulin. a hormone produced by the pancreas. Insulin is a key regulator of the body's metabolism. It normally works in the following way:
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- During and immediately after a meal, digestion breaks carbohydrates down into sugar molecules (of which glucose is one) and proteins into amino acids.
- Right after the meal, glucose and amino acids are absorbed directly into the bloodstream, and blood glucose levels rise sharply. (Glucose levels after a meal are called postprandial levels .)
- The rise in blood glucose levels signals important cells in the pancreas, called beta cells. to secrete insulin, which pours into the bloodstream. Within 10 minutes after a meal insulin rises to its peak level.
- Insulin then enables glucose to enter cells in the body, particularly muscle and liver cells. Here, insulin and other hormones direct whether glucose will be burned for energy or stored for future use.
- When insulin levels are high, the liver stops producing glucose and stores it in other forms until the body needs it again.
- As blood glucose levels reach their peak, the pancreas reduces the production of insulin.
- About 2 - 4 hours after a meal both blood glucose and insulin are at low levels, with insulin being slightly higher. The blood glucose levels are then referred to as fasting blood glucose concentrations .
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Type 1 Diabetes
In type 1 diabetes, the pancreas does not produce insulin. Onset is usually in childhood or adolescence. Type 1 diabetes is considered an autoimmune disorder.
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Patients with type 1 diabetes need to take insulin. Dietary control in type 1 diabetes is very important and focuses on balancing food intake with insulin intake and energy expenditure from physical exertion.
Type 2 Diabetes
Type 2 diabetes is the most common form of diabetes, accounting for 90 - 95% of cases. In type 2 diabetes, the body does not respond normally to insulin, a condition known as insulin resistance. Over time, some patients also run out of insulin. In type 2 diabetes, the initial effect is usually an abnormal rise in blood sugar right after a meal (called postprandial hyperglycemia).
Patients whose blood glucose levels are higher than normal, but not yet high enough to be classified as diabetes, are considered to have pre-diabetes. It is very important that people with pre-diabetes control their weight to stop or delay the progression to diabetes.
Obesity is common in patients with type 2 diabetes, and this condition appears to be related to insulin resistance. The primary dietary goal for overweight type 2 patients is weight loss and maintenance. With regular exercise and diet modification programs, many people with type 2 diabetes can minimize or even avoid medications. Weight loss medications or bariatric surgery may be appropriate for some patients.
General Dietary Guidelines
Lifestyle changes of diet and exercise are extremely important for people who have pre-diabetes, or who are at high risk of developing type 2 diabetes. Lifestyle interventions can be very effective in preventing or postponing the progression to diabetes. These interventions are especially important for overweight people. Even moderate weight loss can help reduce diabetes risk.
The American Diabetes Association recommends that people at high risk for type 2 diabetes eat high-fiber (14g fiber for every 1,000 calories) and whole-grain foods. High intake of fiber, especially from whole grain cereals and breads, can help reduce type 2 diabetes risk.
Patients who are diagnosed with diabetes need to be aware of their heart health nutrition and, in particular, controlling high blood pressure and cholesterol levels.
For people who have diabetes, the treatment goals for a diabetes diet are:
- Achieve near normal blood glucose levels. People with type 1 diabetes and people with type 2 diabetes who are taking insulin or oral medication must coordinate calorie intake with medication or insulin administration, exercise, and other variables to control blood glucose levels.
- Protect the heart and aim for healthy lipid (cholesterol and triglyceride) levels and control of blood pressure.
- Achieve reasonable weight. Overweight patients with type 2 diabetes who are not taking medication should aim for a diet that controls both weight and glucose. A reasonable weight is usually defined as what is achievable and sustainable, and helps achieve normal blood glucose levels. Children, pregnant women, and people recovering from illness should be sure to maintain adequate calories for health.
Overall Guidelines. There is no such thing as a single diabetes diet. Patients should meet with a professional dietitian to plan an individualized diet within the general guidelines that takes into consideration their own health needs.
For example, a patient with type 2 diabetes who is overweight and insulin-resistant may need to have a different carbohydrate-protein balance than a thin patient with type 1 diabetes in danger of kidney disease. Because regulating diabetes is an individual situation, everyone with this condition should get help from a dietary professional in selecting the diet best for them.
Several good dietary methods are available to meet the goals described above. General dietary guidelines for diabetes recommend:
- Carbohydrates should provide 45 - 65% of total daily calories. The type and amount of carbohydrate are both important. Best choices are vegetables, fruits, beans, and whole grains. These foods are also high in fiber. Patients with diabetes should monitor their carbohydrate intake either through carbohydrate counting or meal planning exchange lists.
- Fats should provide 25 - 35% of daily calories. Monounsaturated (such as olive, peanut, canola oils; and avocados and nuts) and omega-3 polyunsaturated (such as fish, flaxseed oil, and walnuts) fats are the best types. Limit saturated fat (red meat, butter) to less than 7% of daily calories. Choose nonfat or low-fat dairy instead of whole milk products. Limit trans-fats (such as hydrogenated fat found in snack foods, fried foods, and commercially baked goods) to less than 1% of total calories.
- Protein should provide 12 - 20% of daily calories, although this may vary depending on a patient’s individual health requirements. Patients with kidney disease should limit protein intake to less than 10% of calories. Fish, soy, and poultry are better protein choices than red meat.
- Lose weight if body mass index (BMI) is 25 - 29 (overweight) or higher (obese).
Several different dietary methods are available for controlling blood sugar in type 1 and insulin-dependent type 2 diabetes:
- Diabetic exchange lists (for maintaining a proper balance of carbohydrates, fats, and proteins throughout the day)
- Carbohydrate counting (for tracking the number of grams of carbohydrates consumed each day)
- Glycemic index (for tracking which carbohydrate foods increase blood sugar)
Tests for Glucose Levels. Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern for patients who take insulin. It is important, therefore, to monitor blood glucose levels carefully. Patients should aim for the following measurements:
- Pre-meal glucose levels of 70 - 130 mg/dL
- Post-meal glucose levels of less than 180 mg/dL
Hemoglobin A1C Test. Hemoglobin A1C (also called HbA1c or HA1c) is measured periodically every 2 - 3 months, or at least twice a year, to determine the average blood-sugar level over the lifespan of the red blood cell. While fingerprick self-testing provides information on blood glucose for that day, the A1C test shows how well blood sugar has been controlled over the period of several months. For most people with well-controlled diabetes, A1C levels should be at around 7%.
Other Tests. Other tests are needed periodically to determine potential complications of diabetes, such as high blood pressure, unhealthy cholesterol levels, and kidney problems. Such tests may also indicate whether current diet plans are helping the patient and whether changes should be made. Periodic urine tests for microalbuminuria and blood tests for creatinine can indicate a future risk for serious kidney disease.
Other Factors Influencing Diet Maintenance
Food Labels. Every year thousands of new foods are introduced, many of them advertised as nutritionally beneficial. It is important for everyone, most especially people with diabetes, to be able to differentiate advertised claims from truth. Current food labels show the number of calories from fat, the amount of nutrients that are potentially harmful (fat, cholesterol, sodium, and sugars) as well as useful nutrients (fiber, carbohydrates, protein, and vitamins).
Labels also show "daily values," the percentage of a daily diet that each of the important nutrients offers in a single serving. This daily value is based on 2,000 calories, which is often higher than what most patients with diabetes should have, and the serving sizes may not be equivalent to those on diabetic exchange lists. Most people will need to recalculate the grams and calories listed on food labels to fit their own serving sizes and calorie needs.
Weighing and Measuring. Weighing and measuring food is extremely important to get the correct number of daily calories.
- Along with measuring cups and spoons, choose a food scale that measures grams. (A gram is very small, about 1/28th of an ounce.)
- Food should be weighed and measured after cooking.
- After measuring all foods for a week or so, most people can make fairly accurate estimates by eye or by holding food without having to measure everything every time they eat.
Timing. Patients with diabetes should not skip meals, particularly if they are taking insulin. Skipping meals can upset the balance between food intake and insulin and also can lead to low blood sugar and even weight gain if the patient eats extra food to offset hunger and low blood sugar levels.
The timing of meals is particularly important for people taking insulin:
- Patients should coordinate insulin administration with calorie intake. In general, they should eat three meals each day at regular intervals. Snacks are often necessary.
- Some doctors recommend a fast acting insulin (insulin lispro) before each meal and a longer (basal) insulin at night.
Special Considerations for People with Kidney Failure
Diabetes can lead to kidney disease and failure. People with early-stage kidney failure need to follow a special diet that slows the build-up of wastes in the bloodstream. The diet restricts protein, potassium, phosphorus, and salt intake. Fat and carbohydrate intake may need to be increased to help maintain weight and muscle tissue.
People who have late-stage kidney disease usually need dialysis. Once patients are on dialysis, they need more protein in their diet. Patients must still be very careful about restricting salt, potassium, phosphorus, and fluids. Patients on peritoneal dialysis may have fewer restrictions on salt, potassium, and phosphorus than those on hemodialysis.
Major Food Components
Compared to fats and protein, carbohydrates have the greatest impact on blood sugar (glucose). Except for dietary fiber, which is not digestible, carbohydrates are eventually broken down by the body into glucose. Carbohydrate types are either complex (as in starches) or simple (as in fruits and sugars).
One gram of carbohydrates provides 4 calories. The current general recommendation is that carbohydrates should provide between 45 - 65% of the daily caloric intake. Carbohydrate intake should not fall below 130 grams/day.
Complex carbohydrates are broken down more slowly by the body than simple carbohydrates. They are more likely to provide other nutritional components and fiber.
Vegetables, fruits, whole grains, and beans are good sources of carbohydrates. Whole grain foods provide more nutritional value than pasta, white bread, and white potatoes. Brown rice is a better choice than white rice.
Patients should try to consume a minimum of 20 - 38 grams of fiber daily (or even up to 50 grams/day), from vegetables, fruits, whole grain products such as cereals and breads, and nuts and seeds.
Whole grains specifically are extremely important for people with diabetes or those who are at risk for it. [For specific benefits, see: "Whole Grains, Nuts, and Fiber-Rich Foods," below.]
Simple carbohydrates, or sugars (either as sucrose or fructose), adds calories, increases blood glucose levels quickly, and provides little or no other nutrients.
Sucrose (table sugar) is the source of most dietary sugar, found in sugar cane, honey, and corn syrup.
Fructose, the sugar found in fruits, produces a smaller increase in blood sugar than sucrose. The modest amounts of fructose in fruit can be handled by the liver without significantly increasing blood sugar but the large amounts in soda and other processed foods with high-fructose corn syrup overwhelm normal liver mechanisms and trigger production of unhealthy triglyceride fats.
A third sugar, lactose, is a naturally occurring sugar found in dairy products including yogurt and cheese.
People with diabetes should avoid products listing more than 5 grams of sugar per serving, and some doctors recommend limiting fruit intake. You can limit your fructose intake by consuming fruits that are relatively lower in fructose (cantaloupe, grapefruit, strawberries, peaches, bananas) and avoiding added sugars such as those in sugar-sweetened beverages. Fructose is metabolized differently than other sugars and can significantly raise triglycerides.
In addition, avoid processed foods with added sugars of any kind. Pay attention to ingredients in food labels that indicate the presence of added sugars. These include terms such as sweeteners, syrups, fruit juice concentrates, molasses, and sugar molecules ending in “ose” (like dextrose and sucrose).
The Carbohydrate Counting System. Some people plan their carbohydrate intake using a system called carbohydrate counting. It is based on two premises:
All carbohydrates (either from sugars or starches) will raise blood sugar to a similar degree, although the rate at which blood sugar rises depends on the type of carbohydrate. In general, 1 gram of carbohydrates raises blood sugar by 3 points in people who weigh 200 pounds, 4 points for people who weigh 150 pounds, and 5 points for 100 pounds.
Carbohydrates have the greatest impact on blood sugar. Fats and protein play only minor roles.
In other words, the amount of carbohydrates eaten (rather than fats or proteins) will determine how high blood sugar levels will rise. There are two options for counting carbohydrates: advanced and simple. Both rely on collaboration with a doctor, dietitian, or both. Once the patient learns how to count carbohydrates and adjust insulin doses to their meals, many find it more flexible, more accurate in predicting blood sugar increases, and easier to plan meals than other systems.
The basic goal is to balance insulin with the amount of carbohydrates eaten in order to control blood glucose levels after a meal. The steps to the plan are as follows:
The patient must first carefully record a number of factors that are used to determine the specific requirements for a meal plan based on carbohydrate grams:
Multiple blood glucose readings (taken several times a day)
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